/*
 * Copyright (C) 2015 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.bonn.fast.net.interceptor.log;

import android.text.TextUtils;

import java.io.EOFException;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.concurrent.TimeUnit;

import okhttp3.Connection;
import okhttp3.Headers;
import okhttp3.Interceptor;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;
import okhttp3.ResponseBody;
import okhttp3.internal.http.HttpHeaders;
import okhttp3.internal.platform.Platform;
import okio.Buffer;
import okio.BufferedSource;
import okio.GzipSource;

import static okhttp3.internal.platform.Platform.INFO;

/**
 * An OkHttp interceptor which logs request and response information. Can be applied as an
 * {@linkplain OkHttpClient#interceptors() application interceptor} or as a {@linkplain
 * OkHttpClient#networkInterceptors() network interceptor}. <p> The format of the logs created by
 * this class should not be considered stable and may change slightly between releases. If you need
 * a stable logging format, use your own interceptor.
 */
public final class HttpLoggingInterceptor implements Interceptor {
    private static final Charset UTF8 = Charset.forName("UTF-8");

    public enum Level {
        /**
         * No logs.
         */
        NONE,
        /**
         * Logs request and response lines.
         *
         * <p>Example:
         * <pre>{@code
         * --> POST /greeting http/1.1 (3-byte body)
         *
         * <-- 200 OK (22ms, 6-byte body)
         * }</pre>
         */
        BASIC,
        /**
         * Logs request and response lines and their respective headers.
         *
         * <p>Example:
         * <pre>{@code
         * --> POST /greeting http/1.1
         * Host: example.com
         * Content-Type: plain/text
         * Content-Length: 3
         * --> END POST
         *
         * <-- 200 OK (22ms)
         * Content-Type: plain/text
         * Content-Length: 6
         * <-- END HTTP
         * }</pre>
         */
        HEADERS,
        /**
         * Logs request and response lines and their respective headers and bodies (if present).
         *
         * <p>Example:
         * <pre>{@code
         * --> POST /greeting http/1.1
         * Host: example.com
         * Content-Type: plain/text
         * Content-Length: 3
         *
         * Hi?
         * --> END POST
         *
         * <-- 200 OK (22ms)
         * Content-Type: plain/text
         * Content-Length: 6
         *
         * Hello!
         * <-- END HTTP
         * }</pre>
         */
        BODY
    }

    public interface Logger {
        void log(String message);

        /**
         * A {@link Logger} defaults output appropriate for the current platform.
         */
        Logger DEFAULT = new Logger() {
            @Override
            public void log(String message) {
                Platform.get().log(message, INFO, null);
            }
        };
    }

    public HttpLoggingInterceptor() {
        this(Logger.DEFAULT);
    }

    public HttpLoggingInterceptor(Logger logger) {
        this.logger = logger;
    }

    private final Logger logger;

    private volatile Level level = Level.NONE;

    /**
     * Change the level at which this interceptor logs.
     */
    public HttpLoggingInterceptor setLevel(Level level) {
        if (level == null) throw new NullPointerException("level == null. Use Level.NONE instead.");
        this.level = level;
        return this;
    }

    public Level getLevel() {
        return level;
    }

    @Override
    public Response intercept(Chain chain) throws IOException {
        Level level = this.level;

        long startNs = System.nanoTime();
        Request request = chain.request();
        Response response = chain.proceed(request);
        long tookMs = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNs);

        boolean logBody = level == Level.BODY;
        boolean logHeaders = logBody || level == Level.HEADERS;

        RequestBody requestBody = request.body();
        boolean hasRequestBody = requestBody != null;

        Charset charset = UTF8;
        String requestBodyString = null;

        if (response != null && level != Level.NONE) {

            if (hasRequestBody) {
                Buffer requestBodyBuffer = new Buffer();
                requestBody.writeTo(requestBodyBuffer);

                MediaType contentType = requestBody.contentType();
                if (contentType != null) {
                    charset = contentType.charset(UTF8);
                }

                if (isPlaintext(requestBodyBuffer)) {
                    requestBodyString = requestBodyBuffer.readString(charset);
                }
            }


            String requestUrl = request.url() + (TextUtils.isEmpty(requestBodyString) ? "" : ("?" + requestBodyString));

            Connection connection = chain.connection();
            String requestStartMessage = "--> request"
                    + ' ' + requestUrl
                    + (connection != null ? " " + connection.protocol() : "");
            if (!logHeaders && hasRequestBody) {
                requestStartMessage += " (" + requestBody.contentLength() + "-byte body)";
            }
            logger.log(requestStartMessage);
            logger.log("method: " + request.method());
            if (logHeaders) {
                if (hasRequestBody) {
                    // Request body headers are only present when installed as a network interceptor. Force
                    // them to be included (when available) so there values are known.
                    if (requestBody.contentType() != null) {
                        logger.log("Content-Type: " + requestBody.contentType());
                    }
                    if (requestBody.contentLength() != -1) {
                        logger.log("Content-Length: " + requestBody.contentLength());
                    }
                }

                Headers headers = request.headers();
                for (int i = 0, count = headers.size(); i < count; i++) {
                    String name = headers.name(i);
                    // Skip headers from the request body as they are explicitly logged above.
                    if (!"Content-Type".equalsIgnoreCase(name) && !"Content-Length".equalsIgnoreCase(name)) {
                        logger.log(name + ": " + headers.value(i));
                    }
                }
            }


            ResponseBody responseBody = response.body();
            long contentLength = responseBody.contentLength();
            String bodySize = contentLength != -1 ? contentLength + "-byte" : "unknown-length";
            logger.log("<-- "
                    + response.code()
                    + (response.message().isEmpty() ? "" : ' ' + response.message())
                    + ' ' + requestUrl
                    + " (" + tookMs + "ms" + (!logHeaders ? ", " + bodySize + " body" : "") + ')');

            if (logHeaders) {
                Headers headers = response.headers();
                for (int i = 0, count = headers.size(); i < count; i++) {
                    logger.log(headers.name(i) + ": " + headers.value(i));
                }

                if (!logBody || !HttpHeaders.hasBody(response)) {
                    logger.log("<-- END HTTP " + request.url());
                } else if (bodyHasUnknownEncoding(response.headers())) {
                    logger.log("<-- END HTTP " + request.url());
                } else {
                    BufferedSource source = responseBody.source();
                    source.request(Long.MAX_VALUE); // Buffer the entire body.
                    Buffer buffer = source.getBuffer();

                    Long gzippedLength = null;
                    if ("gzip".equalsIgnoreCase(headers.get("Content-Encoding"))) {
                        gzippedLength = buffer.size();
                        GzipSource gzippedResponseBody = null;
                        try {
                            gzippedResponseBody = new GzipSource(buffer.clone());
                            buffer = new Buffer();
                            buffer.writeAll(gzippedResponseBody);
                        } finally {
                            if (gzippedResponseBody != null) {
                                gzippedResponseBody.close();
                            }
                        }
                    }

                    MediaType contentType = responseBody.contentType();
                    if (contentType != null) {
                        charset = contentType.charset(UTF8);
                    }

                    if (!isPlaintext(buffer)) {
                        logger.log("");
                        logger.log("<-- END HTTP " + requestUrl);
                        return response;
                    }

                    if (contentLength != 0) {
                        logger.log("--> BODY " + buffer.clone().readString(charset));
                    }

                    if (gzippedLength != null) {
                        logger.log("<-- END HTTP " + requestUrl);
                    } else {
                        logger.log("<-- END HTTP " + requestUrl);
                    }
                }
            }

        }

        return response;
    }

    /**
     * Returns true if the body in question probably contains human readable text. Uses a small sample
     * of code points to detect unicode control characters commonly used in binary file signatures.
     */
    static boolean isPlaintext(Buffer buffer) {
        try {
            Buffer prefix = new Buffer();
            long byteCount = buffer.size() < 64 ? buffer.size() : 64;
            buffer.copyTo(prefix, 0, byteCount);
            for (int i = 0; i < 16; i++) {
                if (prefix.exhausted()) {
                    break;
                }
                int codePoint = prefix.readUtf8CodePoint();
                if (Character.isISOControl(codePoint) && !Character.isWhitespace(codePoint)) {
                    return false;
                }
            }
            return true;
        } catch (EOFException e) {
            return false; // Truncated UTF-8 sequence.
        }
    }

    private boolean bodyHasUnknownEncoding(Headers headers) {
        String contentEncoding = headers.get("Content-Encoding");
        return contentEncoding != null
                && !contentEncoding.equalsIgnoreCase("identity")
                && !contentEncoding.equalsIgnoreCase("gzip");
    }
}
